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71.
HUI XiDong XU ZhiYi WU Yuan CHEN XiaoHua LIU XiongJun & LU ZhaoPing State Key Laboratory for Advanced Metals Materials University of Science Technology Beijing Beijing China 《科学通报(英文版)》2011,(36)
A series of Er-Al-Co bulk metallic glasses (BMGs) have been prepared by the copper mold casting method. The glass forming ability and magnetocaloric effect (MCE) for these alloys have been investigated. The second-order magnetic transition from para-magnetic to ferromagnetic states takes place at about 9 K. These BMGs exhibit excellent MCE because of their large effective magneton number; Er56Al24Co20 BMG has a maximum entropy change and refrigeration capacity of 16.06 J kg-1 K-1 and 546 J kg-1,respectively... 相似文献
72.
ZHANG Rui WU Min WANG Qiang GENG JinJu & YANG XiaoDi School of Chemistry Environmental Science Nanjing Normal University Nanjing China National Marine Environmental Monitoring Centre Dalian College of Environmental Science Engineering Peking University Beijing State Key Laboratory of Pollution Control Resource Reuse Nanjing University Nanjing 《科学通报(英文版)》2010,(16)
Phoshpine (PH3), a volatile and toxic gas, has been proved to commonly exist in the environment.The determination of gaseous phosphine and its emission fluxes in Ny-lesund is reported in this paper.Results showed that gaseous phosphine exist in Arctic atmosphere commonly and the concentration of phosphine ranged from 16.3-600.2 ng/m3, with the maximum concentration of phosphine in tundra areas and the minimum in surface air of ocean.The concentration of phosphine ranged from 65.79-1259 ng/m3 in colliery at... 相似文献
73.
This paper studies the practical generation of Voronoi diagrams for multiply-connected planar areas bounded by line segments. The core of the algorithm was calculating Voronoi polygon of every Voronoi object in planar areas independently. The main approach had two steps. The first step was calculating all relevant bisectors of every Voronoi object. The second was combining obtained bisectors into completed Voronoi polygons individually. All code was implemented in Visual C++ platform. The resulting code was extensively tested in real-world data and its practical running time grew only linearly. Three statistical CPU-consumption charts had been drawn with the Voronoi diagrams computation data, and compared with other published codes for computing Voronoi diagrams. The algorithm was applied to compute offsetting of slice area consisting of large-scale line segments for the selective laser melting (SLM) trajectory scanning technology which is a kind of rapid prototyping (RP). The experimental results of offsetting for slice area based on Voronoi diagrams show that the approach is effective and simple for polygon offsetting problems. The method is helpful to those offsetting work and can provide more effective offsetting solution. 相似文献
74.
The cluster global time can change in wireless sensor networks due to leader re-elections and node disabilities between two successive synchronizations,which will affect temporal relationships.This paper analyzes cluster global time continuity,using global time change models for the node dynamics.The results prove that defining the global time using the cluster average time(AGT) is more stable than defining it using a single node’s local time(SGT).With normally distributed clock-parameter assumptions,the AGT change bounds are at most 70.7% of those for the SGT’s.The impacts of the initial phase and frequency skew distributions on the global time continuity are also investigated to show that the initial phase variations may strongly influence the continuity.Simulations show that the AGT is more stable with less disabled nodes or larger clusters.The appropriate cluster size is 20-40 when there are less than 15 disabled nodes. 相似文献
75.
This paper describes a distributed estimation scheme (DES) for a bandwidth constrained ad hoc sensor network.The DES is universal in the sense that operations on all sensors are identical and independent of noise distribution.The scheme requires each sensor to transmit just a 1-bit message per observation.Simulation results show that the scheme achieves much better mean-squares error (MSE) performance than the simplified isotropic universal DES and even outperforms the isotropic universal DES which requires more than twice the bandwidth of this scheme. 相似文献
76.
Content addressable storage (CAS) is a promising technology for improving storage efficiency as well as access throughput.Currently,many CAS products are implemented on the block level,which results in loss of file information.Thus,some sophisticated optimizations cannot be achieved,such as accurate fileprefetching.This paper presents a file-aware block-level storage system combined with the CAS function.In contrast with some existing file-level CAS,this system is transparent to upper-level applications,including the operating system and the file system.These features are achieved by using smart-disk technologies to help the storage system to learn the file-system layout.A prototype was implemented on an open-source virtual machine (VM) with the guest operating system being Windows XP.Tests show that this combination significantly reduces the size of the VM image file and improves the storage performance by discarding unused blocks and using a simple file-level prefetching strategy. 相似文献
77.
LIU HongJia ZHENG HuaKun WANG Hua GUO Peng ZUO JianRu & TAO YueZhi State Key Laboratory Breeding Base for Zhejiang Sustainable Pest Disease Control 《科学通报(英文版)》2011,(31)
Three allelic short root mutants were identified by screening mutants with defective root elongation of the rice japonica cultivar Nipponbare mutant library generated via 60 Co γ-ray irradiation mutagenesis. These mutants, designated srt7-1 (short root 7-1), srt7-2 and srt7-3, respectively, had an extremely short seminal root, adventitious roots and lateral roots. Histological observation revealed the cell length of srt7 mutant roots was significantly shorter than that of wild-type roots. Genetic analysis i... 相似文献
78.
79.
HE XinBo QU XuanHui REN ShuBin & JIA ChengChang School of Materials Science Engineering State Key Laboratory for Advanced Metals&Materials University of Science Technology Beijing Beijing China 《中国科学:技术科学》2010,(4)
The continuing miniaturization of electronic devices in microelectronics and semiconductors drives the development of new packaging materials with enhanced thermal conductivity to dissipate the heat generated in electronic packages.In recent years,several promising composite materials with high thermal conductivity have been developed successfully for high performance electronic equipment to replace the traditional Kovar and Cu/W or Cu/Mo alloys,such as SiCp/Al,SICp/Cu,diamond/Al and diamond/Cu.However,thes... 相似文献
80.
Direct milling of sand molds is an important development in rapid manufacturing of sand molds. Direct milling is an effective method for manufacturing single or small batches of cast parts. This paper describes experimental investigations to find sand blocks with the appropriate strength, to describe wear patterns of different tools (high-speed steel (HSS), carbide, and polycrystalline diamond (PCD) tools), and to analyze sand mold cutting mechanisms. The results show that the PCD tool outperformes the other tools in terms of tool life. Average flank wear and micro-tipping are the dominant tool failure modes in the sand mold milling process. With a flank wear limit of 0.3 mm, the PCD tool works continuously for about 70 h under the experimental conditions. The experimental results show that the cutting mechanism for direct milling sand molds differs from metal cutting. 相似文献